The photos showed how wild and intense dogs look when their fur, lips and ears are rendered weightless as they chase tennis balls in swimming pools. The images were highly praised for their originality.

This week, Jill Reger—an advertising photographer by trade who shot for hotel and tourism clients in Arizona and Texas—got in touch to say that she had taken a similar series of diving dog portraits.

Her images, however, were taken way back in 1997, when waterproof cameras still used film. So Business Insider asked her to pull them out of her dusty storage locker, where they've been sitting since the late 20th century.

To get the shots, Reger had to solve a technical problem: regular film used underwater produces dull, unimpressive images. Her innovative fix was to use highly sensitive infra-red film with a sepia toner.

The combination produces an otherworldly look in which water appears deep and dark, and living things glow with life.

"I was at a weird stage of not wanting to do photography because it hurt too much."

"Then my nephews came to town and I decided to try the camera."

"I had seen a video of a dog swimming under water 20 years ago, and I thought I needed a light-colored dog. A friend said, 'Oh, I have a friend who has a dog that likes to go diving.' I said, 'What color is it?' She said, 'yellow.'"